Clinical and Immunoserological Status 12 Weeks after Infection with COVID-19: Prospective Observational Study

Introduction

Respiratory infection (COVID-19) caused by SARS-CoV-2 is characterized by asthenia, fever, dry cough, anosmia, arthromyalgia and dyspnoea, and less commonly by nasal congestion, headache, odynophagia, vomiting and diarrhoea. One week into the course of the disease some patients develop a very aggressive inflammatory response that can lead to respiratory failure secondary to adult respiratory distress, septic shock or coagulation disorders [1, 2], which in turn can produce venous thromboembolism [3]. Reports also exist of involvement of the heart [4, 5], nervous system [6], liver, kidney and skin [7] and eyes [8]. Whether these lesions heal definitively or whether they leave persisting damage is unknown. Accordingly, it seems advisable to undertake monitoring and follow-up of patients who have had COVID-19 to determine any possible sequelae [9]. Few data are currently available about the immunoserological response in convalescing patients. Studies have suggested that the serological response with effect from 3 months after symptom onset could reach 100% [10]. Nevertheless, little information exists about the duration of the presence of antibodies in COVID-19 patients. We therefore undertook a multidisciplinary follow-up of all COVID-19 patients seen at our hospital to determine their functional and immunoserological status, assess the presence of possible sequelae and evaluate their course.

Results

Of the original 116 patients contacted 3 (2.5%) refused to attend. Of the remaining 113, 5 (4.4%) were excluded as they proved not to be COVID cases. Table 1 shows the baseline characteristics of the patients during the acute episode. The mean age of the 108 patients was 55.5 (SD: 15.4) years, and 82 (75.9%) had some sort of symptom at the time of office revision. Table 2 shows the symptoms, with a predominance of respiratory symptoms. Concerning the number of symptoms, 18.6% reported just one, 19.5% two and 39.8% three or more symptoms.

*De los patients que estaba disponible **Cifra de linfocitos menor de 900 ICU, intensive care unit; LDH, lactate dehydrogenase A blood test was performed in 102 (94.4%) of the 108 COVID-19 patients. Table 3 shows the main changes, highlighting an increase in D-dimer >500 ng/mL in 32 (31.4%) patients. No significant differences were seen according to the presence or absence of symptoms concerning imaging tests, 89 (82.4%) patients had a control chest radiograph at 12 weeks after the acute episode. In 56 (62.9%) this was normal, in 24 (26.9%) the evolution of the images was favourable and in 9 (10.1%) the radiological alterations seen during the acute phase had persisted or worsened. A chest CT

LDH, lactate dehydrogenase; CRP, high-sensitivity C-reactive protein Spirometry was performed in 32 (29.6%) patients. In 23 (71.9%) the result was normal, 4 (12.5%) had an obstructive pattern, 3 (9.4%) a mixed pattern and in 2 (6.3%) the alterations were interpreted as secondary to poor collaboration. None of the baseline characteristics was associated with radiological or respiratory function changes.

Being a health-care worker was associated with symptom persistence (OR = 4.79 [95% CI = 1.02-22.38], p=0.046), with age ≥65 years being a protective factor (OR = 0.33 [95% CI = 0.12-0.87], p=0.026) (Table 5).

Discussion

Few studies examining the course of patients with COVID-19 have included data about possible sequelae and the immunoserological response against SARS-CoV-2. In our study most of the infected patients (75.9%) in our preliminary SARS-CoV-2 cohort continued to have symptoms 12 weeks after the acute episode. This coincides with the results reported by Carfi et al., who assessed the presence of residual symptoms in 143 patients after a mean of 60 days following the acute episode [12]; 87.4% of the patients reported persistence of symptoms.

Dyspnoea was the predominant symptom in most of our patients. A retrospective study comprising 50 patients assessed one month after the acute episode found that over half presented worsened lung function, mostly consisting of restrictive and diffusion alterations, generally mild [13]. Likewise, the persistence of diffusion alterations seems more common in patients who have severe pneumonia during the acute episode [14]. In our series, the prevalence of alterations detected on spirometry was lower than in the previous series, though our series included more patients with a mild acute episode than the others.

Additionally, as spirometry in our cohort was determined by the persistence of symptoms, a lower percentage of patients underwent the test. Although most of the patients with radiological alterations during the acute phase evolved favorably, 37% still had some degree of persistence of symptoms. The chest CT in these patients confirmed the presence of radiological lesions, most frequently persistence of the ground-glass opacity. This is in contrast to the findings of Zhao YM, et al. [15] who assessed 55 patients three months after acute infection with SARS-CoV-2 and found that 70% has persistence of radiological alterations. However, whereas in our series it was persistence of ground-glass opacity and crazy paving in their series it was interstitial thickening compatible with pulmonary fibrosis [15]. The three patients with fibrosis in our series had presented severe clinical symptoms, with one having bilateral pneumonia and requiring admission to the intensive care unit, which agrees with the literature [16]. Of note is the high number of patients who reported dyspnoea, sometimes with cough and chest pain, but who had no demonstrable respiratory function or radiological alterations. The association of these systemic symptoms together with asthenia and psychological disorders could constitute what has been called post-viral or post-covid chronic fatigue syndrome [17]. The presence of anxiety and depression has been reported with SARS [18] and they may persist beyond the duration of the bout. In our series, 16.7% of the patients experienced psychological or cognitive alterations after the acute episode of COVID-19, which is in concordance with the impact that other outbreaks have had for the mental health of the patients and the community in general [19]. Nine of our patients required psychiatric assessment. The most frequent symptoms after respiratory symptoms were neurological symptoms, occurring in about one in every 10 patients, mainly persistence of headache, anosmia and dysgeusia. The presence of these symptoms during the acute infection is common [6, 20] and although most cases appear to resolve in less than 4 weeks [21], our results suggest that these alterations may persist in some patients for at least three months.

During the acute phase of SARS-CoV-2 there can be involvement of the myocardium, producing myocarditis. Whilst the prognosis for this appears favourable, we are unaware of the long-term consequences of this myocardial damage, and it may be part of the genesis of the palpitations and chest pain sometimes reported by patients at revision [22]. Another important cardiovascular aspect we have noted is the persistence in the rise in D-dimer in over 30% of the patients three months after the acute phase; one of our patients even showed pulmonary thromboembolism on the control CT. This all suggests the need to maintain the patient’s ant coagulated for an indeterminate period [23]. Unfortunately, we are unable to provide a response to this as our study was not designed with this in mind.

Almost all our patients had a humoral immune response by three months after the acute episode. Furthermore, this serological response was independent of the severity of the acute symptoms and the symptoms at the time of revision. Between 2 and 6 weeks after diagnosis of COVID-19 most patients develop antibodies against SARS-CoV-2, as shown in the study by Lin L, et al. [24] that included 334 patients with COVID-19 confirmed by SARS-CoV-2 PCR. Specific IgM or IgG antibodies were detected in all the patients. It has been suggested that asymptomatic patients could seroconvert to a lesser extent than patients with severe symptoms and could even become negative during the convalescence [25]. However, we failed to see this as all our patients had detectable antibodies 3 months after the acute episode.

Subsequent follow-up of our patients will show the evolution of the immunoserological response. Care of patients with COVID-19 has an important impact on the health of health-care workers [26, 27]. This impact has both physical and mental consequences [27]. A retrospective cohort study found that symptoms of infection by COVID-19 in health-care workers are mild or moderate in 91% of cases [28]. Nonetheless, our data show that health-care workers more often have residual symptoms that persist after the acute episode. It would, therefore, be recommendable to undertake an evolutionary follow-up of this group after SARS-CoV-2 infection. Moreover, health-care workers have a greater risk of post-traumatic stress, with the younger workers more often developing this condition [26]. In our study the patients <65 years had a greater risk of residual symptoms.

Conclusion

In conclusion, 12 weeks after the acute episode residual symptoms are common in patients with COVID, the most frequent being respiratory involvement. Health- care workers and patients <65 years have a greater risk of presenting persistent symptoms after the acute episode. An increase in D-dimer suggests the possibility of a state of hypercoagulability persisting after the acute phase. All our patients had developed IgM or IgG antibodies against SARS- CoV-2 by 12 weeks.